(1) Field of the Invention
This invention relates to a motor-driven welding machine construction, and more particularly to a motor-driven welding machine which is capable of holding and carrying various types of welding torches stably and in smooth movements.
(2) Description of Prior Art
In the welding operation with a conventional semi-automatic welding machine, for instance, in CO.sub.2 welding, the torch is moved manually by an operator along a welding line while keeping the tip end of the torch nozzle at a predetermined distance from the workpiece. This sort of manual welding operation is simple but has an inherent drawback in that it is difficult and toilsome for an operator to move the tip end of the nozzle at a uniform speed and at a constant distance from the workpiece. In fact, it is extremely difficult even for a skilled operator to keep on the manual welding operation satisfactorily over a long time period.
It has already been known in the art to provide a motor-driven wheeled carriage for supporting the welding torch, the carriage usually having one or two wheels (with or without an auxiliary wheel). A welding machine on a single- or two-wheeled carriage is put in travel in the welding operation, dragging a power cable of 2 meters or longer. One problem with such welding machine is that it easily looses its balance due to the dragging resistance of the cable or upon application of a localized load, causing a certain wheel to idle or falling down unless supported by the hand of the operator. The instability of the machine is encourage when a torch of a particular shape which has a center of gravity at a higher level is employed for performing a different welding operation.
Therefore, there has been a demand for a welding machine which is adjustable according to the type and shape of the torch to be supported thereon and which can travel in stable state without yielding to the dragging resistance of the cable and irrespective of the kind of the mounted torch. Of course, the welding machine itself is preferred to be compact and light-weighted and the adjusting machinism to be simple in construction.